The invention relates to am electrically controlled fuel injection pump for internal combustion engines. In fuel injection devices of this kind, a pump piston, preferably driven by the engine camshaft, is disposed together with an associated injection nozzle in a common housing. The fuel injection quantity is controlled during the pump piston compression stroke by a quantity control valve, which for space reasons is secured to a laterally projecting housing part.
From a supply tank, fuel is pumped by a feed pump in a low-pressure chamber that communicates with the pump work chamber via a metering line. During the pump piston intake stroke, fuel flows at low pressure via the metering line into the pump work chamber, and during the compression stroke the fuel flows back again into the low-pressure chamber as long as this metering line is open. The quantity control valve is disposed in this metering line, so that in the blocked state, the pressure necessary for injections can build up in the pump work chamber.
Because of the high operating pressures of such fuel injection pumps, a particularly rigid connection between the quantity control value and the pump housing is necessary. In a known fuel injection pump of this generic type (U.S. Pat. No. 4,653,455), the quantity control valve is therefore secured to the projecting housing part, which has an external thread, with a union nut. This arrangement has the disadvantage, however, that providing an external thread on the pump housing is expensive, since in view of the high injection pressures the pump housing is of tempered steel. Another disadvantage is that with such an arrangement it is not possible to carry the metering line in a straight line from the pump work chamber to the quantity control valve; it is instead necessary to embody this portion of the metering line as a high-pressure bore bent twice at right angles. However, a metering line embodied in this way is unfavorable from a hydraulic standpoint, and rounding of the bends is difficult. Additionally, the problem arises of sealing off the bores from the outside in the high-pressure region.